<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="./vue.js"></script>
  <style>
    .box{
      width:200px;
      height: 200px;
      background-color: rgb(185, 163, 35);
    }
    .box2{
      width:200px;
      height: 200px;
      background-color: rgb(16, 241, 136);
    }
  </style>
</head>
<body>
  <div id="box">
    <input type="text" v-model="a">
    <div v-bind:class="a">

    </div>
    <div v-bind:aaa="a"></div>
  </div>

  <script>
    let vm = new Vue({
      el:"#box",//指定vue的控制范围
      data:{
       a:""
      }
    });
  </script>
</body>
</html>